Belt locks of restraining systems, for example, seat belt systems, which can be used in, for example, motor vehicles, are often equipped with status sensors with which proper locking of a tongue of the seat belt inserted in the belt lock can be checked. Knowledge of the locking status of the belt lock is useful to notify the passengers by a signal to put on and fasten their seat belts. Since the introduction of safety airbags, information about the locking status of seat belt systems has also been useful for activating or deactivating mechanisms for inflating driver and passenger airbags or side and head airbags.
In addition to contactless status sensors, for example, Hall sensors, electromechanical systems can also be used to monitor one or more components of the belt lock that change their position—for example, two different end positions—when the locking mechanism is actuated. EP-B-1 585 276 discloses a belt lock in which the locking status can be checked by a mechanically actuatable switch. The switch includes a fixed contact sheet and a contact sheet that is designed as a spring contact and that projects into an axial displacement path of a slide that can be moved between two end positions. In the case of locking, the slide presses against a middle bent region of the spring contact, by which a hammer-shaped contact end comes into contact with the fixed contact sheet. The mechanical switch is housed in a separate chamber of a belt lock housing that is closed to the outside. The movable spring contact projects through an opening of the chamber into the axial displacement path of the switch. Mounting of this switch arrangement in the separate chamber of the belt lock housing is relatively cumbersome and can hardly be automated. In mounting by hand, great care should be taken that the movable spring contract is not bent or crimped.
In Swiss Patent Application No. CH 01644/09, a switch arrangement is disclosed that can be designed as a structural unit that can be mounted as a whole on the top or bottom of a frame of the belt lock. The switch arrangement includes a fixed contact part and an elastic switching contact part that can be designed, for example, as contact sheets. Extensions stretch from the legs of a U-shaped free end section of the switching contact part and project through recesses in the top or bottom part of the frame into a displacement path of a belt lock ejector. When the ejector moves axially out of its first end position in the unlocked state into a second end position in a locked state of the belt lock, it crosses the extensions of the switching contact that project into its displacement path. In this way, the switching contact sheet is exposed to pressure and the otherwise interacting contacts on the fixed contact sheet or on the switching contact sheet of the switch arrangement designed as a normally closed (N/C) contact can be separated. The extensions projecting from the switching contact sheet run substantially perpendicular to its lengthwise extension and project beyond the switch receiver. This engenders the danger that during transport or mounting, they will interlock with other components and can thus be deformed and bent.